Article
Extended Data Fig. 2 | Ruthenium isotope plot showing the ln values of the
measured raw ratios for^99 Ru/^101 Ru and^100 Ru/^101 Ru obtained for 100 ng ml−1
Ru sample solutions and associated Alfa Aesar Ru bracketing standards. The
measured isotope ratios are shown as raw ratios uncorrected for mass-
dependent fractionation and are normalized to reference ratios R and R’. Two
distinct mass fractionation lines can be observed. The slopes for both lines are
indistinguishable within error and are in very good agreement with the
predicted slope of 0.5, which would be expected if the exponential law could
accurately correct the mass-dependent fractionation (see Methods for details).
Most importantly, the samples purified by distillation fall on the same
respective mass fractionation line as their associated Alfa Aesar bracketing
standards. This clearly demonstrates that the Ru distillation does not induce
any unaccounted mass-fractionation effects for the samples in comparison
with the bracketing standards. The shift observed for samples and associated
standards plotting on a distinct mass fractionation array was caused by a
maintenance on the mass spectrometer in May 2019, during which a Faraday
cup was changed. However, this does not affect the accuracy of the isotopic
data because the analysed samples and their associated bracketing standards
are shifted by the same magnitude, and the isotopic data are expressed as ε
values from the bracketing standards.